Polyurethanes incorporating fire-retardant compositions are well-known. Urethane polymers incorporating 2,3-dibromo-2-butenediol-1,4 as a chain extender and reactive fire-retardant component have also been suggested more recently and this diol has been found to impart particularly advantageous fire-retardant qualities.
However, it has been proposed heretofore to secure optimum fire retardancy, particularly in foamed polyurethane resins, that the bromine component and phosphorus component, from whatever source derived, be present in a weight percent ratio of one to the other of P + Br/10 = 1.5. This ratio, while providing foams incorporating a desirable fire retardancy and other desirable physical and mechanical properties, involves the emission of a substantial volume of smoke, in the event combustion occurs, and substantial expense, as well.
If the smoke emission properties of polyurethanes could be reduced, together with the cost of manufacture, and the mechanical properties of these polymers retained and enhanced, it is obvious that a long-felt need would be fulfilled and, consequently, a significant discovery effected.
This need exists particularly with respect to polyurethane foams and most particularly with respect to flexible slab and high-resilience polyurethane foams where the flammability and smoke-emission properties of the foams which are used, particularly in bedding and furniture applications and in automotive deep-molded seat cushioning, is a matter of obvious concern and increasing governmental interest. At the same time, an improvement of the mechanical and physical properties of these foams including high resilience and load ratio, high tensile strength, higher elongation and greater tear strength together with significant improvement in hysteresis and fatigue would constitute a significant and unexpected advantage prized by purchasers and users of these foams.